Hydroxyapatite-coated acetabular components - Histological and histomorphometric analysis of six cups retrieved at autopsy between three and seven years after successful implantation

Citation
A. Tonino et al., Hydroxyapatite-coated acetabular components - Histological and histomorphometric analysis of six cups retrieved at autopsy between three and seven years after successful implantation, J BONE-AM V, 83A(6), 2001, pp. 817-825
Citations number
35
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Ortopedics, Rehabilitation & Sport Medicine","da verificare
Journal title
JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME
ISSN journal
0021-9355 → ACNP
Volume
83A
Issue
6
Year of publication
2001
Pages
817 - 825
Database
ISI
SICI code
0021-9355(200106)83A:6<817:HAC-HA>2.0.ZU;2-3
Abstract
Background: Important questions remain regarding the use of hydroxyapatite- coated acetabular components in total hip arthroplasty. What is the relatio n of resorption of the hydroxyapatite coating to enduring fixation? Will un resorbed or dislodged hydroxyapatite particles cause adverse tissue reactio ns? Retrieval studies of clinically well-functioning acetabular components should help to answer these questions. Methods: We examined six clinically successful hydroxyapatite-coated cement less acetabular components that were retrieved at autopsy between 3.3 and 6 .6 years after implantation. Ail components were of the same design. The pr ostheses and the surrounding bone were prepared for qualitative histologica l and quantitative histomorphometric analysis. The percentage of bone growt h onto the implant, the relative bone area around the implant, the extent o f residual hydroxyapatite coating, and the coating thickness were measured. Results: All of the cups showed bone ongrowth, with a mean bone-implant con tact land standard deviation) of 36.5% +/- 13.5%. The contact area was the same in all three zones delineated by DeLee and Charnley. The extent and th ickness of the hydroxyapatite layer were much reduced in the specimens from older patients and in those associated with a longer duration of implantat ion. Degradation of the hydroxyapatite coating by osteoclasts was observed. We did not observe loose hydroxyapatite granules far from the coating, nor did we note any adverse tissue reaction: to these granules. In contrast, p olyethylene debris was noted in approximately half of the empty Conclusions: Cell-mediated hydroxyapatite resorption seems to be the main r eason for loss of hydroxyapatite coating. The area of bone ongrowth was wit hin a certain range (20% to 50%) of the measured surfaces, and it was indep endent of the amount of hydroxyapatite residue. The hydroxyapatite coating showed a slow rate of resorption with time, without any adverse tissue reac tions.